74VHCT257A(2004) Просмотр технического описания (PDF) - STMicroelectronics

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74VHCT257A
(Rev.:2004)

QUAD 2 CHANNEL MULTIPLEXER (3-STATE)

STMicroelectronics 

74VHCT257A

QUAD 2 CHANNEL MULTIPLEXER (3-STATE)

s HIGH SPEED: tPD = 4.8 ns (TYP.) at VCC = 5V

s LOW POWER DISSIPATION:

ICC = 4 µA (MAX.) at TA=25°C

s COMPATIBLE WITH TTL OUTPUTS:

VIH = 2V (MIN.), VIL = 0.8V (MAX)

s POWER DOWN PROTECTION ON INPUTS

& OUTPUTS

s SYMMETRICAL OUTPUT IMPEDANCE:

|IOH| = IOL = 8 mA (MIN)

s BALANCED PROPAGATION DELAYS:

tPLH ≅ tPHL

s OPERATING VOLTAGE RANGE:

VCC(OPR) = 4.5V to 5.5V

s PIN AND FUNCTION COMPATIBLE WITH

74 SERIES 257

s IMPROVED LATCH-UP IMMUNITY

s LOW NOISE: VOLP = 0.8V (MAX.)

DESCRIPTION

The 74VHCT257A is an advanced high-speed

CMOS QUAD 2-CHANNEL MULTIPLEXER

(3-STATE) fabricated with sub-micron silicon gate

and double-layer metal wiring C2MOS technology.

It is composed of four independent 2-channel

multiplexers with common SELECT and ENABLE

INPUT(OE). The VHCT257A is a non-inverting

multiplexer. When the ENABLE INPUT is held

"High", all outputs become high impedance state.

SOP

TSSOP

Table 1: Order Codes

PACKAGE

SOP

TSSOP

T&R

74VHCT257AMTR

74VHCT257ATTR

If SELECT INPUT is held "Low", "A" data is

selected, when SELECT INPUT is "High", "B" data

is chosen.

Power down protection is provided on all inputs

and outputs and 0 to 7V can be accepted on

inputs with no regard to the supply voltage. This

device can be used to interface 5V to 3V since all

inputs are equipped with TTL threshold.

All inputs and outputs are equipped with

protection circuits against static discharge, giving

them 2KV ESD immunity and transient excess

voltage.

Figure 1: Pin Connection And IEC Logic Symbols

December 2004

Rev. 3

1/13

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